In the drilling and completion industry, the formation of boreholes for the purpose of production or injection of fluid is common. The boreholes are used for exploration or extraction of natural resources such as hydrocarbons, oil, gas, water, and alternatively for CO2 sequestration.
Surface-controlled, subsurface safety valves (“SCSSV's”) are typically used in production string arrangements to quickly close off the production borehole whenever a particular situation warrants such action. A usual form for an SCSSV is a flapper-type valve that includes a flapper member. The flapper-type member or simply flapper member is pivotally movable between open and closed positions within the borehole. The flapper member is actuated between the open and closed positions by a flow tube that is axially movable within the borehole. The flapper member is urged by a spring to its closed position.
The flapper member is arranged to be moved to the open position in response to a supply of hydraulic fluid pressure from a remote source at surface that acts on the flow tube. In response to the exhaust of such hydraulic fluid pressure, the flow tube is cycled back to a resting position under spring force and the flapper member is allowed to close. The SCSSV requires seals to separate portions of the SCSSV at control line pressure and portions of the SCSSV at tubing string internal pressure.
Moving the flow tube axially downhole can also be accomplished using electromagnets having concentrically arranged, tubular shaped, radially polarized magnets that interact to move the flow tube in an uphole or downhole direction. In either case, movement of the flow tube axially downhole using hydraulic or electromagnetic force must overcome the spring compression force that biases the flow tube in an uphole direction.
The art would be receptive to additional devices and methods for moving the flow tube, as well as dealing with sealing friction encountered by prior art designs.